Light detection and ranging (LIDAR) is a method of sensing distances of distant objects by using reflected light, usually from a laser. LIDAR systems may be used in different terrestrial, airborne and mobile applications. For example, LIDAR systems may be used to generate high-resolution maps in airborne geo-mapping applications, ground-based surveying, underwater scanning, and the like. In addition, LIDAR systems may be used in “radar guns” by police to monitor traffic speeds. In addition, LIDAR systems may be used in automotive applications for driver assistance situations and/or self-driving cars. Typically, these LIDAR systems have a range and field of view to detect objects, such as other automobiles, at an appropriate distance to take any necessary action, such as warning the driver or changing the speed of the automobile.
LIDAR systems could operate on the basis of various types of optical output signals, such as continuous wave Doppler, pulsed Doppler, continuous wave phase-shift keying (CW-PSK), pulsed PSK, and the like. As an example, the LIDAR system emits a short pulse of infrared light that is directed in a narrow beam toward a selected target. The light pulse strikes the target and is reflected back towards the LIDAR system. The reflected energy is captured by an optical receiving element and is converted from light energy to an electrical signal. A high speed clock is used to determine the total trip time, which can then be used to calculate the range to the target. In another application, for calculating speed of a target, multiple ranges are taken and the change in range over a short period of time is determined. The maximum range that a LIDAR system can achieve is proportional to the amount of energy emitted per pulse by the light source. There is a need in the art to increase range and/or accuracy of the LIDAR systems.